Aircraft air conditioning system



Feb. 16, 1960 v 'w. c. SHAW v AIRCRAFT AIR.CONDI-TIONING SYSTEM Filed Nov. 50, 1955 5 Sheets-Sheet 1 INVENTOR.

14644 75/? c. s/mw ATTOR/V'YS Feb. 1 19 0 w. c. S HAW 2,925,255

AIRCRAFT AIR CONDITIONING SYSTEM Filed Nov. 30, 1955 5 Sheets-Sheet 2 F/G, 6. w

Feb. 16, 1960 w. c. SHAW 2,925,255

AIRCRAFT AIR CONDITIONING SYSTEM Filed Nov. 30, 1955 3 Sheet-Sheet 3 F/6 Z 290 2a v INVENTOR. WAL TER C. sl-lflW Zdu/w% HTTOR/VEYS AIRCRAFT-AIR. o nmoNnvG sYsrnMF Walter 0. Shaw, East Hartford, cam. assiguor to United ration of neiavym; V Application November so, 1955, Serial No. 549,999 7 Claims. 31, 257-216) Aircraft Corporation, Hartford, Conn., a corpo This invention relates to an improved 'airconditioning system and, more particularly, tov an air conditioning system for an aircraft. I

- It is the general object of the central system to supply all or substantially 'all. of the requirements aboard an aircraft for conditioned-air; whether. the requirements relate 'to pressure conditioned air, to. temperature conditioned-air, or to both'pressure j and temperature conditioned air.

- A furtherobject of the invention is to provide an over-f allair conditioning system'whichis dependable and .,automatic inoperation, requiring as the only manuaLoperation the preliminary setting .of control" devicesrsuch as" invention to provide one" The system.shwn"i n Fig.-l v t V supply an aircraft where :the requirements for conditioned air are many and-are different= or-varied. In fd fili thatthe' advantages of the system may {:be fullyappreciated, let" it be assumed that the aircraft includes a pilot s-cabin C which must bess'uppliecl with air' under" pressure and at a'temperature selected byj'the pilot;'-tha'tt a compartment A**inust be supplied with air under pres" sure which is not criticaLbut which differs from a cabin pressure which the'pilotwouldfselect for comfort and at a temperature'which would not ordinarilybe selected by thepilot; that a compartmentB has a temperature I at any given time; that a pilotsG suit and one or more On-Oil switches,. temperature and pressureselectors and like control elements which require-only infrequent attention or adjustment. i 5

There are other, more specific to those skilled in the art from the following description taken in connection with the attached drawings. i'I he" drawings show but one embodiment of the invention- :and, as will be seen by. the claims forminga part or this 5 specification, the invention embraces other'embodiments .and equivalents of that shown in the drawings wherein,

Fig. 1 is a schematic view of an airconditioningsystern' raszmay be provided inaccordance with the invention;

7 v objects as wellas advantages of the inventionwhich will become apparent:

' indicated at 10 V and- 12,

Fig. 2 is an enlarged view, taken from Fig; 1,-;of thev means providing a source of air at controlled pressure;

to operate valves, valve actuators and other control devices within the system; 1

Fig. 3 is an enlarged view, taken fromj-Fig. 1,- of the :manual control elements; t i

Fig. 4 is an enlarged view,taken from Fig. 1, ofthe :means for opening and closing the compressed air supply -.conduit for the system;

.Fig. 5 is an enlarged view,v taken from 1, the

:means for controlling-temperature in the main air conduit to the aircraftcabin; wFig. 6 is an enlargedyiew, taken Fig. 8 is an enlarged view, taken from 1., Qffthe; valve mechanism :for controlling flow inthe putside air.

conduit to the cabin windshield; and

Fig. 9 is an enlarged view, taken from 7 from Fig. 1, ofithe means for maintaining and controllinga pressure drop Fig. i, or the ram air inlets. and control elements associated therewith.

As the description of the invention progresses, it will become apparent that an air conditioning'system can-be provided in accordancewith this invention to supply many different compartments, devices; and components of an aircraftwith conditioned air whether such com f partmentsdevices, etc. all have need for an at the same pressure and temperature or whether the requirements necessitate supplying the=various compartments,devices,

etc. with air at various pressures and/or temperatures.

.pleniented' requirement, 'butno pressure requirement; that a pilots space suit (not shown) requires -air at a pressure a 'con'" trolled or selected amount" gi'eater than cabin pressure flightin'struments require air at afsubstantially constant pressure; that a cabin windshield de-fogging device (not shownyrequires air on the inside of the windshield at a higher temrseraturethan -would be selected for-pilot comfort; that strain-rem val d vice; requires-airat another temperature; and' lef it be, runner assumed that air must flow 'fro'm'the" system under pressureto the fuel" tanks of the aircraft 'to assure'iproper fuel control.

system'ef Fig. 1 whichsatisfies all ofthejafore aid requirements utilizes ram air andhicli m'ay'b e taken" from the aircratts" engineicompres'sori 'I'hes ystem also requires 'a source of "air atfa substantially constantpressure to operate valve'actuators and pthei' control devices within thesystem; thefsaid, sou e also receiving its air supplyffrom Theair conditiorun compressed air the 'engine -compress'o There "are'two' ram air inlets aud-"there 'are'two compressed air inlets indicated at 14 and 16,' their ilet14- introducing compressedair to thelsystem per s'egan'd "the inlet 16 in rodueing comptessed to constanfipressure source or pressureregulating means 18 which supplies the' airoperated 'control devices in thef'system.- w

- {fhe ra'm air inlet10 is in-a conduit20 which extends tqgtheeompmmeq manaare supply'the said compartmehts-with aeobungstresm'stair; It'will he observed that the ramcooling air is-iiitroduced to a jacket 22 surroundingf the compartment which must be. pres; suriz'ed Thus, thef ram cooling air, which is not pressure controlledfwill not be permitted'to mix with pressurized air introduced to the'cornpartment 'A within the jacket 22 through a conduit iat. As will be more fully appreciated hereinafter, the air in conduit not only pressurizes the comp'artmentiA butjals'o helps to cool that compartment and the co'rnpartme'ntB; *Tha't is, the pressurized air in the interior of the compartment A will cool that compart mentand arn through a conduit' gam the com-i partment B'where it intermiltes with ram 'air'before disl charge tan.. t2 Th fra fi a n he jacket 2; is I dischargedthroughan outlet 30. 3 While the compartment B is opento atmosphereat. the outlet '28, pressure maintainedwithinjtlie''compartnientA by placinga ti limiter or restrictor 32 in the transfer conduit 26.

The pressurized air in conduitg24 is the only coo p air provided for the'conipa r tments A and B undencer tain .condit ions and under all .other conditions it issupw-'lhat is there are/times -when theram .air 1 J toohdt properly. to cool the compartments and the ram inthe conduitltlzand is adapted to close said conduit.-

whenthe ram air temperaturereachesorexcecds a preselected, ,or known point, for: examplei-:140'- 5 F; The valve 34"is-adapted to open;the"ram conduit'20 whenithe ram air. temperaturezdrops to or below apreselected or known point, as for example F. The

-.'Patentedl=feb. m nace particularly adapted to The ram air inlet 12 is ina conduit 36 extending to a heat exchanger 38 which effects heat exchange between ram air and compressed air introduced to. the system at the inlet'14. The ran; air flowing through the heat exchanger 38.provides the cooling medium thereinxand the ram air flow is assisted by a turbine driventsuction fan 40 which discharges the ram air. from the aircraft at the outlet42. The turbine driving the fan 40 is indicated at 44, the, said turbine being driven by compressed air flowing in a conduit 46. extending from the heat exchanger 38 to the said turbine. The compressed air inconduit 46,, which has been cooled in the heat exchanger 38 is further cooled by expansion'in the turbine 44 before it is, discharged to a main cold air conduit 48. The pres: surized cold air conduitlei for the compartment A ex: tends from the main cold air conduit 48.

It should be understood that while the temperature of ram air introduced to the system at the inlet lgamay be quite high under certain flight conditions, the ram air temperature under any anticipated condition will not exceed the compressed air 7, temperature. Therefore, the ain r n ys be used as a c oling me um in the heat exchanger 38 and it is not necessary to provide a temperature responsive shut-off valve in the ram air conduit- 36. However, there are certain conditions of p n, k n. to occu only ur n ar u d up, h r s i ions o ext r al y nduce .s t t e r m n et a e uch ast so duce h .flow and ns ty o e am r as to Pe m ov pe in o h urb ne 4 a d tanv 40- To d is undes a l esult, an ambient air inlet is provided in the ram air conduit 36 (see Fig. 9) The said ambient air inlet is normally closed by a flap valve 52 but will open when there is inadequate ram air flow or pressure and the turbine driven fan 49 can draw air through the inlet 50 to oid tu o e s edi While the ram air conduit36 contains no temperature responsive shut-off valve, it has been found convenient to locate a temperature sensitive unit 54 therein, the said unit being operatively associated with the shut-off valve 34 in the ram air conduit 20. As best seen in Fig. 9, the unit 54 comprises a bowed or curved metal plate 56 which is secured at its periphery within a chamber 57 defined within a casing 58 disposed in the conduit 36 So that the chamber 57 receives ram air therein. The b ed P te il be u e in d ect o shown (for example, concave outwardly with respectto con,- duit 36) when the ram air does not reach or exceed a t i rq n a fo exam hen r ir temperature reaches or exceeds approximately 140 F., he Pl e i l snap through center and be curved in the opposite direction (concave inwardly with respect to conduit 36). The plate will remain in the last mentioned position until the ram. air temperature drops to or below a certain point, as for example 110 F., then the plate will resume the first mentioned position.

The plate 56 carries with it a valve 60 which closes an opem'ng 62 into a vent chamber 64 when the plate is in the position shown. When the plate assumes the other, or 'high temperature position, the valve 60 opens thevent chamber to permit the discharge of air through an outlet 66 andthe said valve closes the inlet 68 to a flow chamber 70 The flow chamber 70 also has an' outlet which is connected by means of a conduit 72 to an actuator 74 forvthe valve 34. The inlet of the chamber 70 -is-eonnected by a conduit 76 with the regulated preseure source means 18, the regulated pressure air received therefrom being used in operation of the valve actuator 74. The said valve actuator comprises a bylin der '78 containing a spring biased piston 80 which is opposed within the cylinder by air from the "pressured-egulator 18. When the temperature responsive plate 56 and valve .60 are in the position shown, air flows from t the regulator 18 to the actuator 74 to retain the valve 34, in the open position shown. When the plate 56 is shifted to the other described position as a result of an increased ram air temperature, the conduit 72 is vented so that the actuator piston may be moved by spring force to close the valve 34. Therefore, the temperature responsive unit 54 is the means employed to cause opening and closing of the valve 34 in the ram air conduit 20.

It will be readily understood that means for regulating the pressure of compressor air. to the needs of the valve actuator .7 other control elements can be supplied in a variety 0:. forms. The regulator. 18 shown in-Fig. 2 comprises a housing 82 having two partitions 8 4 and 86 defining, in top-to-bottom order, an inlet chamber 31, a flow chamber 6;, and apiston chamber 85. A piston-like valve 88 is disposed within the housing to extend through the said partition, the valve being biased within the piston chamber to open a flow aperture in the partition 84 between the inlet and flow chambers. The inlet chamber 81 is connected with a conduitQb having the compressed air inlet 16 whereby compressed air may flow through the inlet chamber into the flow-chamber 83 within'the housing 82; A controlled pressure drop from the inlet chamber to the flow chamber is effected by providing the upper endof the valve 88 with a taper which will variably restrict the flow aperture between the inlet chamber and the flow chamber; The position of the valve 88, and thus the amount ofopening between the inlet chamber and flow chamber, is controlled by the air pressure in the flow chamber 83 and piston chamber 85. That'is, an aperture 92 isprovided in the partitionv 36 so that air will flow into the piston chamber and opposethe biasing force on the piston in such a direction as to close the aperture between the inlet chamber and the flow'chamber. Thus, if pressure in the how chamber and piston chamber increases, the opening between the vinlet and flow chambers will become more restricted to increase the. pressure drop thereby decreasing thev pressure in the flow chamber and piston chamber. Flow throug'h the flow chamber 83 is discharged into a main regulated pressure conduit 94, but in the event that pressure in the flow chamber and in the con duit 94 exceeds a predetermined level, the excess pressure will be relieved through anopening in the flow chamber normally closed by a relief valve or check valve 96,.

As a result, the means 18 provides a source of air at a regulated pressure which is carried in a conduit 94. The conduit 76 supplying air to the ram air valve actuator 74 communicates with the main regulated pressure conduit Q4 as do all of the other conduits which will be described and which carry servo air for the various control valves valve actuators, and control elements. The main regulated pressure conduit 94 may conveniently be extended to the pilots i-suit and to the flight instrument or instruments or to other devices requiring a supply of air at a substantially constant or regulated pressure. Such extension of the conduit 94 is indicated at 98.

The compressed air inlet 14 is disposed in a conduit extending to the alternator (not shown) for the aircrafts power supply. A conduit which communicates with the conduit 100 delivers compressed air to the air conditioning system. A How limiting device 104, preferably of the Venturi type; .is disposed in the conduit 102 to assure sufficient flow to'the alternator, if the ducting leading to or within certain portions of the air conditioningfsystem should become disconnected.

The tlow of air in the conduit 102 can be shut oif by a poppet valve 1.96 which is operated by pneumatic actnatingmeans best shown in Fig. 4. The said actuatns m an 1 is n automa icall r l s but 'is ally controlled at a remote position by pilot operate d m a enai a 3- I p e va 0 is View??? erable.

by a' diaphragm-piston 108;" disposed within a housing '110 having an air chamber 112 and a spring'charriber 114. Theair' chamberllZ receives compressed air from the conduit 102 through a' restricted passageway 3116 surrounding thepoppet valve 106and the pressure of the'air interconnection. The con referred'toas the mixed air conduit because it may contain a pressurizedniixture of cold air-and hot air;

within-said-chamber against*theldiaphragm-piston '108 normally opens the poppet valve 106 which is biased to- The conduit 154 will at'all times receive'cold air from the conduit 48 'but it-will-receive-hotair'from the. conduit 144 only when a valve 156 is opened therein. Aswill be describedjhreinafter, the v'alve'156 is automatically wards closed positionby-a spring-ll 8 disposed within the spring chamber 114. It 'will be observed thatthe poppet valve" 106 can be closedtoshut ofiE the supply of compressed air to the 'air conditioning systemby vent;

ing'the air chamber 112.

I 'Ihe air chamberlln has a ventoroutlet 120 which is f normally closed byfl'a pilot valve: 122 connectedwith a diaphragm-piston" 124 within a,housing, 1 2 6. It will be, observedthat the pilot valve 122. is spring bfiased towards open position and that when the pilot valve 122 is 'opened, the air, from' the air chamber 112 can be I discharged duced pressure in thechamber 130.3

The manually operable valve 7 136. is avent valve I the example-"shown, the mixed airiconduit "154 supplies wiu'ds'hield through a; conduit 160.

which is opened to cause closing of'the compressed air' conduit 102 at any time desired. "As shown in" the draw;

ings, the valve136 is opened by thrustingfit inwardly andthis can be accomplished by thrusting inwardly a control knob 138. When the ,valve 136 is opened, compres sed air is released from the conduit 134 into a com partment 140 which is vented'to' atmosphere as shown at 142. The conduit 134 and pilot valve chamber 130 being vented, thepilot valve 122 will be displaced to vent the poppet "valve air chamber 112.whereby the, spring biased poppet valve 106 in the compressed airv conduit 102 will close to shut off the compressed air supply'to the system thereby making 'the' system inop:

When the shut-elf valve 106 is openas shown, hot

' compressed air in the conduit 102 will flow theret'hrough' to the heat exchanger 38 wherein it'is cooled. The heat is exchanger 38 iepreferablyv a multiple stage exchanger having compressed air outlets containing air'at different temperatures. More specifically, one such"compressed air outlet conduit is indicated at 144 wherein the temperature is relatively high but nonetheless lower than the temperature of the compressed air in the conduit 102. This conduit 144 will hereinafter be referred to as a hot compressed air conduit within the system. Another compressed air outlet conduit 146 may also operated to close or to be opened to varying degrees to admit a desired amount of'hot air to the mixed air con-- duit 154. The mixed air conduit may be employed to supply various compa'rtr'r'i'entsand devices aboard the aircraft; with pressure and temperature controlled --air. In

air to the cabin C through a conduit 1 58"andalso supplies air toja "de fogging device on the inside of the cabin Pressure within thef ed' air air line 154 through a conduit 166. The housing 164 has an open top which is normally closed by a valve dome 168. --A threaded stem,170 extends through said dome and is connected at its'bottom'end with a spider 1'72 providing aseat for a vertically extending spring 174.

The spring'1 74 wh-ich isrenga'ged withinpthe housing 7 164;biases* the spider 172 and thus the valve dome 168, downwardly to close the said dome 'on' the housing. flWhen air pressure within the mixed air conduit 154 and. theother conduits'mentioned above exceeds a preselected v -maximum,fit will "lift the dome 168 from'its seat to discharge air and thus relieve pressure within the said conduits. I The pressure level atwhich thle escape valve or dome 168 will open (the upper limit of pressure within I the mixed air conduit and the other'conduits) maybe se-r lected by, adjusting anexternally disposed nut 176 on: the

stem 170 so as to adjust the compression of the spring.

174 which holds the valveor dome 168 closed.

, Precise control oi theipressure in the mixed air line" '154'at levels below the selected maximum is not essential to successful operation of, the air conditioning system; 7

- However, at least' some pressure control "or regulation within the conduit 154 is reflected by controlling the prescarry air at a relatively high temperature while additional conduits 148, 150, and 46 will carry 'compressed air at a relatively low temperature, these conduits being arranged to receive compressed air after ithas passed throughthe last stage of heat exchange. The conduit 46, as previoiisly mentioned, extends to the turbine tonsupply the driving air therefon 'Theaiigfrom the: conduit 46 gives up more heat in expansion-within the turbine 44 and. is relatively cold when it flows into the,

conduit 48. The conduit 150 may be extended to the 1 fuel tanks. (not shown),,or to other deviceson the .air-

craft to supply the same with necessary air pressure. The

conduit 148, in the example shown, extends outside-of the cabin C to vthe rain removal device (not-shown) will bemore fully described: hereinafter It will be. observed that the main cold 7 and the main hot air conduit 144 are interconnected :at

152 and that a; conduit 154 extendsnfrom ,saidflpoint of.

a; conduit 4 1 sure within the cabin C. That is, the cabin may be provided with manually or automatically operable 'valve means such as indicated generally at -so that cabin. pressure can be adjusted to a comfortable level. Adjustment of the pressure within the cabin C will be reflected in the pressure existing 'in'the conduit 154. It is vimportant to provide means for maintaining a pressure drop within the conduit 154 on the downstream side of the "pressure relief means 162. The means providing the pressure drop andrthe purpose thereof will be describedhereinafter. i a 7 It is, of course, desirable to provide means whereby a pilot or occupant of the cabin C can select the temperature,

of the compressed air introduced and it isdesirable to have 'means capable offautomatically controlling the temperature after selection has'been'jrnadef. As previously mentioned, t'he'valv'e'j156 dis'posedzin the hot air conduit'144 controls the flow of hot'air to the niixed air conduit where'-. by the mixed air temperature can 'efiebti ely be controlled.

There are various actuating"devicesfyvhich are tempera ture responsive and which' miglit be employed to operate thevalve.1 56.- ,F or example, valve operating means of'the type disclosed in' the JamesS Sims, Jr. et aliapplication;

Seriab-No. 471,152, filedNovernber 26, 1954, could be employed in thissystem;

The'valveractuator employed here and as, shownlin Fig.- a is somewhat similar tothe'means shown in'the aforesaid application.i- The said means includes a housing'1 82 V wherein a diaphragm-piston- 184 is disposed; the saidp tonbeingbiased in meditation by a spring 186'and duit -154 willfhereinafter be p line 154 andpressure' within the hot air line 144' and the cold air lines 48 and 24 isQlimited-to a selected maximum by'means indicated 7 generally at 162. The said pressure limiting means com. prises a housing {164which is connected with the mixed' ture responsive.

biased in the other direction by compressed air within a chamber 188. The chamber 188 receives compressed air from a conduit 190'which communicates with the main regulated air conduit 94 extending from the pressure regulating valve means 18. It will be observed that the diaphragm-piston is connected by a linkage indicated generally at 192 with the valve 156 to adjust its position within the hot air conduit 144. Fluid pressure acting upon the diaphragm-piston through the linkage 192 causes the valve 156 to be opened while the spring 186 acts upon the diaphragm-piston to'close the valve 156 within the hot air conduit. Adjustment of the position of the valve 156 to adjust the temperature in the conduit 154 is effected by varying the air pressurein the chamber 188.

The means for varyingthe said air pressure is tempera- The said temperature-responsive means includes a temperature sensing element 194 which is dis posed in the mixed air conduit 154 and which is. electrically connected by an electrical conduit 1% to an electrical control unit 198 within the cabin C. The said unit 198 is connected to the ships electrical power supply by the lines L1 and L2 and has a line or electrical conduit 200 extending to the valve actuator housing 182 and connected with a proportional solenoid 202 therein. The electrical circuit connections for varying the energy to the solenoid 202 in response to temperature changes sensed by the element 194 form no part of the present invention. However, such a circuit may comprise a bridge network which includes the element 104 as a resistor subject to variation with temperature changes. The said network may also include a variable resistor controlled by the knob 133 which the pilot manipulates in selecting a desired cabin temperature. Variation in the resistor 194 as a result of temperature change in the conduit 154 may unbalance the bridge network so as to vary the electrical energy supplied to the solenoid 202. The circuit can be so arranged that a decrease in temperature within the conduit 154 will decrease the energy to the solenoid 202. As shown in Fig. 5, the solenoid is arranged to move a pivoted armature 204 in a counterclockwise direction as a result of in creased electrical energy. The armature 204 is biased in a clockwise direction by a spring 206, so that when the solenoid energy is reduced, the spring 206 will rotate or pivot the armature.

Rotation of the armature 204is utilized to vary the air pressure in the chamber 188 by extending a conduit 208 from the said chamber toward the armature 204, the extending end of the conduit 208 being provided with a nozzle 210 which can be closed by the armature when. it is pivoted as far as possible in the clockwise direction. When the nozzle is completely closed, the pressure in the chamber 188 will be sutficient to move the diaphragm-piston to completely open the valve 156. When the armature 204 is removed a slight distance from the nozzle 210, pressure within the chamber 188 will be reduced at least a slight amount so that the valve 156 will start to close. As previously mentioned, the armature is pivoted in the counterclockwise or nozzle-opening direction by the solenoid as a result of a temperature increase in the conduit 154. If the said temperature increase is substantial, the energy to the solenoid 202 will be relatively high and the armature will be pivoted a greater distance in the nozzleopening direction. As a result, the pressure in the chamber 188 will begreatly reduced thereby causing the valve 156 to be closed. Fluctuation of the valve 156 is damp- 206 is compressedby the valve operating linkage, 192

when the valve is moved toward aclosed position, thereby ened by a feedback. That'is, the armature-moving spring.

increasing the" fluid pressure in 'the'chamber 188 so as to fully open the valve 156, e

As previously mentioned, it is desirable to maintain and control a pressure dropin' theconduit 154 on the downstream sid e of the pressure limiting means 162. The means for maintainingand controlling the pressure drop in the conduit 154-is best shown in Fig. 6 and comprises a throttle valve 212 in the line 154, a throttle valve actuator 214'and control means 216 for the actuator 214. Itwillbe observed that the throttle valve 212 is disposed downstream of a conduit 218 extending from the mixed air conduit 154. The conduit 218 supplies compressed air to a pilots space suit which should receive a supply of air at. a pressure greater than the cabin air pressure in the conduit 1 58 and in the conduit 154'0n the downstream. side of the valve 212. It isthe purpose of the valve 212 to assure that pressure will'be maintainedin the conduit 218 at greater than cabin pressure. and the valve 212 also assures maintaining pressure in the cold air conduit 24 at a level greater. than cabin pressure. Thus, the throttle valve 212 provides the means for maintaining pressure in compartments and devices. within the aircraft in excess of the pressure in the cabin. In addition, the throttle valve 212 can be closed to maintain pressure in such compartments and devices when no cabin pressure is needed.

The valve actuator 214 includes a housing 220 having a diaphragm-piston which defines an air chamber 222 and a spring ehamber224-within the housing. The diaphragm-piston is connected to the valve'212by a'me-- chanical linkage including a link 226. extending through the housing 220. Air pressure acting uponme' diaphragm-piston tends toopen the valve 212in the conduit 154 and spring forces acting upon the diaphragm-piston tend to close the valve 212. Adjusting the valve 212-in various open positions in the conduit 154 to control the pressure. drop therein is achieved by varying. or. ad justing the pressure in the air chamber 22. vThe air cham ber 222 is connected by a conduit 228 with a flow chamber 230 in the actuator'control means 216. The fiow chamber 230 is connected by a conduit 232 with the main regulated pressure conduit 94 extending from the pressure regulating valve 18. The actuator control means 216 is a device for comparing air pressure on the downstream side of the valve 212 with air pressure on the upstream side of the valve 212 and for adjusting pressure in the flow chamber 230 in accordance therewith so as to adjust air pressure in the actuator 214. More specifically, the control means 216 comprises a housing 234 having two partitions 236 and 238 defining three chambers within the said housing. The said chambers comprise in top-to-bottom order the fio'w chamber 230, a vent chamber 240, and a working chamber 242. A diaphragm-piston 244 is disposed within the working chamber 242 and is exposed on one side to air within the conduit 154 upstream of the valve 212. On the other side of the diaphragm-piston, air is introduced from the downstream side of the valve 212 through a passageway 246. A stem 248 extends from the diaphragm-piston through the partitions 236 and 233 into the flow chamber 230. A spring seat 250 is secured to the stem 243 within the flow chamber 230 and a spring 252 is seated thereon and on an adjustable seat. 254. The seat 254 is adjusted by a screw 256 to vary the force biasing the piston stem 248 and thus the diaphram-piston from the downstream side of the valve 212. The spring biasing force is supplemented by air pressure within the working chamber 242 from the downstream side of the valve 212. Accordingly adjuStment of the spring seat by the; screw 256 will adjust the biasing force on the diaphragm-piston so that the said piston will movedownwardly when the difference in p v ssure across the valve 212 from the upstream to the downstream sides thereof is less than a selected amount which has been selected by adjustment of the screw 256. Downward movement of the diaphragm-piston 244 and-the piston stem 248 as moved toward closed position in the conduit means a result' of a pressuredrop across the, valve "212 which,

a is less than the.selectedminimum:is used to causepara mum and: the piston stem 248 moves downwardly, the

valve disk ';258'. :isunseated in the aforesaid aperture .so that air may -fiow from the flow chamberlzfalllto the vent chamber .240land be discharged therefrom- 'through one or. more ventopen'ings; 260; Discharge or ventingof the air? :from' -,the flow chamber .230.:will; *of mum; irlducei the; air pressure "in the'actfuatoizair chamber- 222 which;

aspreviouslyfl described; causes'aathe z;valV'e"-2l2 to "be 7 154'to'increase the pressure drop thereacross; i 1 Accordingly,.the,zvalve 212, the valve actuator 214 flnd:,the;control device 1216 provide means for maintain Furthermore, openin'g the valve 268 to 'vent "the air chamber 222 in the-valveactuator 214 does not vent all of the at controlled*pressureifrom the main regulated pressure conduit 94' More specifically, a restrictor 3 276 is provided' inthe regulated pressure conduit 232 to maintain pressiire'within the'main regulated pressure conwithin the-cabin" inlet condiiit 158'and in the mixed air conduit'lS L-To provide'an increased temperature in ing a pressure drop which will always be at le'as'tas great; as ,a preselected minimum. As a 'resultf-flow through the conduit 218 to"the.pilot space suit'and'flow through the cold ,a'ir conduit :24: to'ythe" pressurized fcompartrnent A is always assured; The pressure drop across the Naive 212 can be controlled so as-'not to exceed a preselected maximum, if desired; :That is, means .canjtbe' employed to limit the movement ofthe .throttlevalve212? r in jhe closed direction; 'Such means can "conveniently beassoci'ated. with. the. link .226; whichqextends'f through-i the actuator 214.: {For example, an; extension 262' of adjustable effective length can be securedto :the' free end of the l n -226 to engagev with a stop 264"after1the linkfl 226 has 'moved a selected distance corresponding to closinggmovement of-1the'valve .21'2 .t o apreselected" maximum; closed position.-

The aforesaid maximum closed position of the valvef 212-may .be a completely closed position within the" condigit 154 and, in any event; the said: maximum closed position ;-may 3 be employedwhen it 'is-desired to shut the pressure of; air flow ltheretogto -a relatively low" level; I ;This selective -positioi'lingt50f;the;- t'lirottle valve 212 in the maximum closed position is eflected by manual manipulation 'ofan on-off'sele'ctor 266shown in Fig; 3.

V The selector 266 when shifted to the-off? position opens; a valve 268 in a conduit 270*which communicates with theair chamber 222 inithe valve actuator 214. The

valve 268, then vents'the conduit 270.andthe air cham-' Vber;2 2 2 to close the throttle'valve'212. The air vented from.the-conduit" 27tl1flows intothe previously mentioned compartment; 140 andthrough'the ventcondu'it 1421 for discharge from the aircraft :An" additional vent for :the, compartment 140 is. preferably provided and comprises a-vent conduit 272 :which :is op'ened' and closed by a valve274 operating withthevalve 268.

, 1 The manually-operableyalves268. and'.274 are opfi le by th e gswitclr'element1266pnly ,When 'ait'fiis' desired. to

shut off a pressured supply of air to,the cabin C; This does notshu tndown alloperatign oizthe air. conditioning 4 system, fbut. on1y shuts down the. supply of pressured air I to {the cabin. m ;The, SyStem will continue "to asu'p perature. changes {therein to'open and close 'a nozzle 290 cluit Mylar-ing the aforesaid-venting; Similar restrictors,

which are'similarly identified-by the reference 276, are employed in the various regulated pressure conduits extending from the main regulated :pressu-re conduit 94 to the various "valve actuators and control"devices which,

have been d'escribed' andQwhich will bedescribed hereintliefres'tric'tors 27 6 serve the same purpose, namelypto maintainpressurewithin the main regulated pressure vcoiiduit*94"-when thev'arious control valves, etc.

are vented and even-wnenthe' air'condi tioning system is completely'shut'down. f 1

Y Under most 'dperating'conditions it -will;be desirable to have the air within thefde fogging or de-frosting conduit 160 at a temperature greater than that maintained the condu'it l which communicates with the mixed air conduit l54,fi-' -the*iwarm' air conduit 146 extending from theheatj exchanger 38 is connected tothe conduit 160 at the point" 280';'-' .Under some-roperating conditions, the air fin the cond "t"146 when m'ixedwith the air inwthe conduit; 161! may au'se 'the'tmperature thereof to rise." Therror ia throttle valve;282- is} if conduit 146 to=govern:"the fiow' 11 into the conduit 160. A- valveactuator more .than esi disposed-i therethrougli -a indicated gene" Ily at 284iand best; shown in Fig. positions-@t'he' wall/ 55 282 within 'the'warm 'air conduit 146.

The v'alve actuat'or 284 is'responsive totemper'atures of the mix'e'd' a'irwithi'n theconduit 160wher'eby the tem' peraturfe: is semgovemednrrhe said conduit. will be readily understood that various types of temperature responsivei mchanisrns'might be employed for the afores'aidpurpose, one'suchtype beingthat disclosed; for regu lating the temperature lin the conduit 154. The means employed here'forcontrolling the position of the valve 282 and 'thus for controlling temperature in the 'de-fogging 'co'nduit IGO-are'thesame means shown in the application 1 of' l=arkas'et-ial entitled f-Temperature Responsive Control'Valve," and 'filed' of even date herewith. 'Asmore; specifically described in the aforementioned application-of Farkas et al., the temperature responsive valve control means includes a temperature sensor indicated generally at 286. 'The' said'temperature sensor comprisesa bimetallic strip 288 exposed to mixed air within the conduit-160 and which is responsive to temon th'eend of a'conduit 292"extending to the valve actuator 284. The conduit" 292 also is in communication with the inai'nregulated pressure conduit 94 through interconnecting conduits 294 and 296.]Theconduit 294 'is also -ctnnie'cfed through a conduit 2% tothe actuator ply" the otherdevices and compartments .aboardthefair craft lfrorn the mixed air conduit 154@with:pre'ssured' air some; upstreamside; of the throttleevalve By limiting-the, maxirnunrgclosed positioniiofithe. throttlei. I

valve 212- to less than" a',fully-c1osed Zposition, the cabin can continuegto receive-warm;airthrohgh :thecabin l inlet 158 but atno substantial pressure."fln'zaddition,

the de-fogginggconduit: 160 .tosth e 5 inside of: the cabin windshield will icontinue to; receive warm airlrbut at no; substantial pressure. The airi conditioning is 'come 5 pletely, shut ofi only when -the,,valve 136 .isopened' by' nedirection whereby to shift the I valve by a ing 306F-"lhe bimetallic strip 288 may be affected ha i s 4 considered l as an --mcrease in' temperature,v to open; the

nozzle 290 thereby hleeding -theline 292 to-decrease pressure on an 'arinature 308" within the actuator" 284" so as to'bleed another nozzle 310 communicatingwith; the air chamber 300. I As a result,ipr'essure' within the air chamber zilmlswill 'bereduced 't'o'permit'the spring to shift thefvalve 82 in fwhat must b' a clos N 7 jdu'ce ath'e amounzer flowing. throughthe "con;

duit146 -into' thefde fogging1 conduit 160;; Reduction in v v the temperaturecontrol knob.138asapreviouslydescribed; :the warrnflow willj of coursepreduce themixedair direction to re;

p v I v chamber 300Kthere'in; under.

pressure with the chamber- 3'00 forc'es adiaphlfagnrv n in erconnecting' linkage indicated 'general f g phragrn-piStQn isbiased in member" I direction to n1ov e the valve 292 in the other ldirection 'ratiirewhichj, for example; may be em e u n h s .dess in c n u t will be ea u er t od at a de ease in he ed ai te perawre in th t e-t les nduit 160 ll c u e e bimetallic strip 288 to close the nozzle- 290 which will effect closing of the nozzle 3 1!) in the actuator 284 to increase the pressure in the air chamber 300 and to effect an opening of the valve 282. When the valve 282 is moved in the open direction, more warm air is intro: duced to the de-fogging, eonduit 160 so as to increase the temperature therein. a

As previously mentioned, the conduit 148 extending fromthe heat exchanger 38 provides an airlsource for the outside of thewindshield for a rain removing device or the like. Such air on theoutside of the cabin windshield is primarily used to accelerate evaporation and removal of rain and moisture from the outside surface of the windshield. It will be readily understood that re a w m a r can h ed to: t s pu pose n that critical temperature control is not necessary. The only control within the conduit 148 is effected to open selectively to close said conduit, The means opening and: closing the conduit comprises a valve 320 which is operated by air air pressure actuator 322. More specifically (see Fig. 8), theaetuator 322 includes ahousing 324 having a diaphragmrpiston therein defining a spring chamber 326 and an air chamber 328 on opposite sides of the said piston. Air is supplied to the chamber 328 through a conduit 330 which is connected in a'valve 332 with the regulated pressure conduit 296 (Fig. 3).

Air under pressure in theconduit 330 and the chamber" 328 forces the diaphragm-piston in one directionto open l e 320.. e v 32 m y be c osed y spring force when the valve 332 (Fig. 3) is manuallypositioned by control means 334 to close the regulatedpressure conduit 2% and open the conduit 330 to a vent 336. Accordingly, the valve 332 is operated by the pilot to open or close the rain removal conduit148. Obviously, it will be desirable to close the conduit 148 at all times except when moisture collects on the. outside of the cabin windshield. i

It will also be desirable to close the inside windshield conduit 160 to the flow of hot air except for thetime' that it is necessary to remove condensate from the inside of the windshield. This is effected by a manually operable control element 338 which is similar to the element 334 and which controls a valve 340 disposed be tween the regulated pressure conduit 29 4 and the regua. 'rr r QRd Ji 29 That is h n the p o does not want to have warm air blowing on the inside of the cabin windshield, he manipulates the control 338 so, that the valve 340 will close a conduit 342 extending from the valve to the regulated pressure conduit 2 96 and at the same time venting the conduit 294 through the valve 340. This will, of course, reduce the air pressure in the valve actuator 284 so as to close the throttle valve 282 in the warm air conduit 146. v

While the air conditioning system shown has been described with reference to a particular installation which includes specific devices such as the inside and outside windshield de-fogging elements, the'pressurized comparta ment A, and the pilots space suit, it will be readily understood that the system can be used to supply additional and/or other devices which are aircraft components or carried by the aircraft. Therefore, it should beunderstood that the invention is not limited to an airconditioning system supplying the particular elements and, devices mentioned. Obviously, the system can be adapted to serve many and diverse purposesasreilected in the scope of the claims which follow,

A s liitifiuia s m o an a c having a I e i t r u rin m era u e. nd; r s u c n it n ir i s h vin or c r n at a t n ev ee e r at greater than cabin pressure and also having or carrying at. l t Qu e e dev se eq it es-a r. at re ter th n.

cabin temperature, the said system being adapted for con nection with a source of: air under pressure and comprising heat exchanging means, a main pressurized air conduit, a cold air supply conduit extending from the heat exchanging means and connected with said main conduit, two warm air supply conduits extending from said heat exchanging means and one of which is connected with said main conduit, a conduit extending from one of said connected conduits to the one device, valve means disposed in said one warm air conduit and responsive to temperature in said main conduit to control theflow of warm air thereto whereby to control temperature in said main conduit, pressure relief means in said main conduit for limiting pressure therein, a valve adjustably disposed in'said main conduit downstream of said relief means and downstream of said conduit extending to the one device, valve operating'means' for adjusting said valve to maintain a pressure drop in said'm'ain conduit, said valve operating means including control means responsive to pressures on the upstream and downstream sides of said valve, a cabin inlet conduit extending from said main conduit downstream of said valve, conduit means extending from said main conduit to the said other device downstream of said cabin inlet conduit, the other warm air conduit and said conduit means being interconnected, and valve means disposed in said other warm air conduit and responsive to temperature in said conduit means to control flow in said other warm air conduit whereby to control temperature in said conduit means.

2. An air conditioning system for an aircraft having a cabin requiring temperature and pressure conditioned air and having or carrying at least one device requiring air at greater than cabin pressure and also having or carrying at leastone other device requiring air at greater than cabin temperature, the said system comprising a main pressurized air conduit, a cold air supply conduit connected with said main conduit, two warm air supply conduits one of which is connected with said main conduit, a conduit extending from one of said connected conduits to the one device, valve means disposed insaid one warm air conduit and responsive to temperature in said main conduit to control the flow of warm air thereto whereby to control temperature in said main conduit, pressure relief means in said main conduit for limiting pressure therein, a valve adjustably disposed in said main conduit downstream of said relief means and downstream of said conduit extending to the one device, valve operating means for adjusting said valve to to maintain a pressure drop in said main conduit, said valve operating means including control means responsive to pressure on the upstream and downstream sides of said valve, a cabin inlet conduit extending from said main conduit downstream of said valve, conduit means extending from said, main conduit to the said other device downstream of said cabin inlet conduit, the other warm air conduit and said conduit means being interconnected, and valve means disposed in said other warm air conduit and responsive to temperature in said conduit means to control flow insaid ing at least one other device requiring air at greater than cabin temperature, the said system comprising a main pressurized air conduit, a cold air supply conduit connected with said mainconduit, two warm air supply conduits one of which is connected with said main conduit, a

conduit'extending from one of said connected conduits to the one device, valve means disposed in one of said connected supply conduits and responsive to temperature insaid main :conduit to control flow in said one supply conduit whereby to control temperature in said main, conduit, pressure'relief means insaidmain conduitresponsive totemperature in said conduit means downstream of said other warm air conduit'tocontrol flow in ture in said conduit means.

pressure drop in said main conduit, said valve operating means including control means responsive to pressures on the upstream and downstream sides of said valve, a cabin inlet conduit extending from said main conduit downstream of said valve, conduit means extending from said main conduit to the said other device downstream J of said cabin inlet conduit, the other warm air supply conduit and'said conduit means being interconnected, and

valve means disposed in said other warm air conduit and said other warm air conduit whereby to-control tempera- 4. An air conditioning system for an aircraft having a cabin requiring temperature and pressure conditioned air and having or carrying at leastone'device requiring air at greater than cabin pressure and also having or carrying at least one other device requiring'air at greater than cabin temperature, the said system. comprising, a main pressurized air conduit, a' cold air supply conduit connected with said main conduit, two'warm air supplyconduits one of which is connected with said main conduit, a conduit extending from one of said connected conduits to the one device, valve means disposed in one of said connected supply conduits and responsive to temperature in said main conduit to control flow in said one supply conduit whereby to control temperature in said main conduit, pressure relief means in said main conduit for limiting pressure therein, a valve adjust'ably disposed in said main conduit downstream; of said relief means and downstream of said conduit extending to the one device, valve operating means adapted to adjust said valve to maintain a pressure drop in said main conduit,

said valve operating meansjinclu'ding control means responsive to pressures on the upstreamand downstream sides of said valve, a cabin inlet conduit extending from said main conduit downstream of said valve, an inlet conduit extending from said main conduit to the said other device downstream of said cabin inlet conduit, the other warm air supply conduit and the inlet conduit for said other device being interconnected, and valve means disposed in one of the last mentioned interconnected conduits and responsive to temperature insaid interconnected inlet conduit to control flow and thereby to control temperature in said interconnected inlet conduit.

5. An air conditioning system for an aircraft having a cabin requiring temperature and pressure conditioned air and having or carrying at least one device requiring air at greater than cabin pressure and also having or carrying at least one other device requiring air at greater than cabin temperature, the said system comprising a main pressurized air conduit, a cold air supply conduit connected with said main conduit, two warm air supply conduits one of which is connected with said main conduit, a conduit extending from 'oneof said connected conduits to the one device, valve means disposed in one of said connected supply conduits and responsive to tem- "and downstream of the conduit extending to said one device, valve operating means adapted to adjust said valve to maintain a pressure drop in said main conduit, said valve, operating means including control means responsive to pressureson the upstream and downstream sides of said valve, a cabin inlet conduit extending from said main conduit downstream of said valve, and conduit means extending from said main conduit to the said other device downstream of the cabin inlet conduit, the other warm air supply conduit and said conduit means being interconnected.

6. An air conditioning system for an aircraft having a cabin requiring temperature and pressure conditioned air and having or carrying at least one device requiring air' at greater than cabin pressure and also havingor carrying at least one other'device requiring air at other than cabin temperature, the said system comprising a main pressurized air conduit, a plurality of cold air sup- 'ply conduits one of which is connected with said main 20 conduit, a plurality of warm air supply conduits one of which is connected with said main conduit, a conduit extending from one of said connected conduits to the one device, valve means disposed in one of said connected supply conduits and responsive to temperature in said main conduit to control flow thereto whereby to including control means responsive to pressures on the vupstream and downstream sides of said valve, a cabin inlet conduitrextending from said main conduit downstream of said valve, and conduit means extending from said mainconduit to the said other device downstream of the cabin inlet conduit, another of said supply conduits being connected with said conduit means.

l 7. An air conditioning system for an aircraft having a cabin requiring temperature and pressure conditioned air and having or carrying at least one device requiring air at greater than cabin pressure, the said system comprising a main pressurized air conduit, a cold air supply conduit connected with said main conduit, a warm air supply conduit connected with said main conduit, a conduit extending from one of said connected conduits to said one device, valve means disposed in one of said supply conduits and responsive to temperature in said main conduit to control flow in said one supply conduit whereby to control temperature in said main conduit, a valve adjustably disposed in said main conduit'downstream of said conduit extending to said one device, valve operating means adapted to adjust said valve to maintain a pressure drop in said main conduit, said valve operating means including control means responsive to pressures on the upstream and downstream sides of said valve, and a cabin inlet conduit extending from said main conduit downstream of said valve.

References Cited in the file of this patent V UNITED STATES PATENTS 2,327,664 Otis Aug. 24, 1943 2,654,580 Shaw Oct. 6, 1953 2,655,174 Towler et a1. Oct. 13, 1953 2,661,763 Renick Dec. 8, 1953 2,696,975 Massey et a1. Dec. 14, 1954 r 2,772,621 Arnoldi Dec. 4, 1956 

